A proton exchange membrane fuel cell (PEMFC) includes an anode, a cathode and a membrane between the anode and cathode. In one example, hydrogen gas is fed to the anode and air or pure oxygen is fed to the cathode. At the anode, an anode catalyst causes the hydrogen molecules to split into protons (H+) and electrons (e−). The protons pass through the membrane to the cathode while the electrons travel through an external circuit to the cathode, resulting in production of electricity. At the cathode, a cathode catalyst causes the oxygen molecules to react with the protons and electrons from the anode to form water, which is removed from the system.
The membrane is oriented between the cathode catalyst layer and the anode catalyst layer. The catalyst layers and the membrane define a membrane electrode assembly (MEA) or a catalyst coated membrane (CCM). The CCM can be formed by a decal transfer process. In a decal transfer process, a catalyst ink is applied onto a decal to form a catalyst layer. The catalyst ink used to form the catalyst layer commonly contains an ionomer, a supported catalyst and a solvent. The decal can be formed, for example, of Teflon® by DuPont, USA. The decal/catalyst layer assembly is then arranged on the membrane with the catalyst layer adjacent to the membrane, and the assembly is hot pressed to transfer the catalyst layer to the membrane. Following hot pressing, the decal is peeled off or removed, leaving the catalyst layer on the membrane. An anode catalyst layer and a cathode catalyst layer can be applied to the membrane in this manner.
Platinum supported on carbon is typically used as the catalyst in PEMFCs. In order to reduce material costs, it is desirable to use low platinum loading electrodes, such as electrodes having a platinum loading of about 0.4 milligram platinum or less per square centimeter of electrode (mg Pt/cm2). One method for reducing loading involves reducing the thickness of the catalyst layer. However, thin catalyst layers (i.e., less than about 4 microns) are difficult to create using a decal transfer process.